DERMATOGLYPHIC P R I N T S : NEGLEC TED RECORDS I N RACIAL ANTHROPOLOGY HAROLD CUMMINS Department of Anatomy, Tulane University This is published with the hope that it may stimulate more extensive collection of records f o r racial studies of the epidermal-ridge configurations, o r dermatoglyphs. While a sufficient amount of work has been done to demonstrate that racial dermatoglyphic traits do exist, larger collections and a representation of many races a r e needed. Since the prints can be made so readily, there is reason to believe that the need will be met when those who a r e in contact with the material recognize the potential usefulness of these records as well as the small outlay i n equipment and effort necessary to obtain them. The collection of prints is urged not only because of laggard progress i n dermatoglyphic investigation, but also on account of' the fact that they afford a means of extending the correlation of somatic traits within a racial sample. When circumstances admit the assembling of comprehensive records, prints may well be secured, supplementing other records which a r e prepared f o r later analysis in the laboratory. Ideally, the foregoing recommendations should be accompanied by a review of what already has been accomplished, with an indication of specific deficiences which call most urgently for attention. It should be important to note, for example, that our own North American Indians are not represented in the list of published racial studies. While a review is hardly feasible within the limits of the present note, i t is, in fact, really unnecessary, for so little has been done that the systematic collection of prints .within any racial 31 ANERICAN J O U R N A L O F PHYSICAL ANTHROPOLOGY, VOL. XVI, NO. 1 JULY-SEPTEMBER, 1 9 3 1 32 HAROLD CUMMINS group will yield data of value. Wilder’s comment that study in this field “. . . . has been no more than begun” is perhaps more cogent at the present time than when it was written in 1916, since the accomplishment since then has opened up still more territory which awaits study. Bibliography relating to racial studies may be consulted in several papers appearing in previous volumes of this journal (Keith ; Wilder; Cummins; Cummins and Midlo). An analysis of the Eskimos is carried in the present number. Prints of the palmar and plantar surfaces, for study of the dermatoglyphs, possess a distinct technical advantage over many of the records employed in physical anthropology. The making of prints requires only the most simple and inexpensive equipment, and is, moreover, neither a very time-consuming procedure nor one necessitating detailed acquaintance with the features recorded. Yet if the prints are to be entirely satisfactory, it is essential to observe certain practices in their preparation. This note provides a brief technical guide for those who are unfamiliar with the dermatoglyphs, and it embodies such directions as the writer has found needful in instruction in printing. Passing t o the prints themselves, attention may be turned first to the character of an adequate racial sample. The number of individuals represented should naturally be as large a s possible, since the ultimate analysis is statistical in nature. The frequencies of various dermatoglyphic elements a r e the chief basis of racial comparison, hence the determinations have stability in direct ratio ta the number of individuals providing them. Ordinarily, prints of one hundred o r more subjects should be secured, though this statement must not be taken to discourage the collection of prints when only a smaller series is obtainable. I n some instances the racial characters a r e so distinctive that they a r e reliably indicated in a limited series, and even when this is not the case, the smaller collections represent an advance in the assembling of d a t a - o f importance particularly in the instance of the less commonly accessible peoples. DERMATOGLYPHTC PRIXTS 33 I t is a matter of practical interest that individuals of any age a r e suitable subjects, the dermatoglyphs undergoing no morphological change with growth and advancing age. Infants, however, a r e not favorable from the standpoint of printing technique, their hands being difficult to manage and the ridges so delicate that prints made by the usual method are often mere smudges. (When prints of infants a r e desired, as in inheritance studies, the photopaper method devised by J. H. Mathews is recommended; for a n account of the process see Am. Jour. Phys. Anthrop., vol. 12, pp. 422 4 2 4 . ) The usual precautions to control the racial composition of the sample should be applied, of course. I f members of families a r e represented in the collection, the relationship should be recorded. I n a collection assembled a s a racial sample it is desirable to exclude close relatives, for they may bring into the series familial peculiarities which by their frequency mask the true racial traits. Sexual variation in dermatoglyphics appears at present to be an almost negligible factor in the composition of a racial collection. Thus i t is possible to determine the racial trend in a series composed wholly of one sex or of the sexes in any proportion. Still, certain minor sexual differences have been reported, and it is well to secure when possible a fairly equal representation of the sexes. With respect to the parts which should be printed, it may be stated that the goal toward which to work is an actually complete record of the dermatoglyphs in each individual : fingers, palms, toes, and soles. There are practical difficulties in the way of securing toe prints, as may be evidenced by the fact that the literature contains but one racial analysis of these features (Hasebe, '18, toe prints in one hundred Japanese). While this state of affairs should in itself be an incentive to investigate the toe patterns, failure to secure the impressions is no iiidication that other prints need be foregone. A series consisting of finger prints, palm prints, and sole prints is feasible, and effort should be made to secure 34 EAROLD CUMMINS this complement of records f o r each individual. There may be occasions, however, in which f o r one reason or another it is impossible to print the subjects to this extent, in which case the writer urges that the palms and fingers be obtained. If there is choice in the matter, these prints are to be preferred, both f o r the character of the dermatoglyphs and for ease of printing. I n suggesting the following particulars with regard to printing there is no intention to indicate that only such equipment and method a r e appropriate, f o r any worker will in course of time have his own preferences. The suggestions, however, a r e based upon actual use of various devices, and the recommendations a r e made in accordance with their working simplicity and quality of results. SUPPLIES Paper Sheets of letter size (84 x 11 inches) a r c well adapted to the present use. Letter bond of good quality serves thc purpose, but the prints a r e improved if made 011 smoother paper (bond with a n enameled surface). It i s unwise to risk the permanence of the prints by using a grade of paper which may become tendcr with aging, but if no better is to be had, one map conserve the prints by mounting the sheets on a substantial backing. Ink The ink marketed f o r the mimeograph serves excellently in printing, and requires 110 preparation for use. Unless it is obtained in a collapsible tube, a small wide-mouth bottle having a cork fitted with a brush or swab should be provided as a container from which the ink may be daubed upon the printing slab. Roller A small rubber roller is needed for spreading ink. While the softer composition roller used by printers is especially adapted to the purpose, the type employed in photographic work is quite suitable. DERMATOGLYPHIC PRINTS 35 Printing slabs Two printing slabs provide rigid, smooth surfaces, upon one of which ink is to be rolled, while the other serves to support the paper while the print is being made. Glass slabs, which are often used, are clearly unfitting if the equipment is to be safely portable. Slabs with a working surface as good as glass may be made by backing sheets of polished copper, tin, or brass with wood, care being taken that the metal is perfectly plane. The slabs must be large enough to accommodate the foot; a length of about 12 inches is suggested, and the width should not be less than about 6 inches. ‘Pressure pad’ The palm, with its irregular reliefs, will require special manipulation jf all its surface is registered in the print. While other devices have been suggested, the sponge-rubber cushion employed by Strong (Science, vol. 69, p. 250, 1929) is recommended. Strong describes the pad as follows: The material employed for the pressure pad is a variety of sponge rubber bearing the trade name of ‘Spongtex,’ which is sold by office-supply dealers in the form of chair cushions. It is about 17 mm in thickness, with plane surfaces, one of which is felt. For the purpose under discussion it should be cut into rectangular slabs of convenient size (e.g., 15 x 15 cm), and the felt-covered sides of two slabs glued together with a liberal supply of Le Page’s glue, applied to both slabs. Too much weight placed on the slabs while the glue is drying will result in subsequent warping of the pressure pad. THE GENERAL METHOD To be in fit condition f o r printing, the hands and feet must be clean and dry. (The subject may be assured that the ink washes away readily with soap and water.) The ink slab and roller are to be kept free from dust and grit. The principle of dermatoglyphic printing is the same as printing from type, involving simply the application of ink to discrete elevations and their impression against paper. The skin ridges are appreciably raised, adjoining ridges being separated by distinct grooves, and it is their summits which 36 HAROLD CUMMINS carry the ink in printing. A daub of ink is placed upon the ink slab, and with the roller it is spread into a thin, uniform film. The quantity of ink is of prime importance, the chief need being to guard against a n excess. The optimum quantity may be determined with a few trials, and experience will dictate the amount requisite to secure prints which show the skin ridges clearly defined. Transfer of ink from the film rolled on the slab to the summits of the skin ridges is effected by pressing the finger, palm, or sole to the film; hence, if there is too much ink, it will be squeezed into the sulci between the ridges, blurring the resulting print. The degree of pressure applied in inking and printing also demands notice. Excessive pressure tends to flatten the ridges and to squeeze ink between them. Inspection of the ink slab after an impression has been made from it will show that the film bears a negative print of the dermatoglyphs, since the film has been depleted at all points of contact with the skin ridges. Should another impression be made from the film without effacing this negative print by rolling, the second impression will surcharge it and the print will consequently exhibit innumerable minute lapses in the courses of the ridges. It is thus necessary to roll the ink slab between successive impressions except in printing the fingers, which may be impressed one after the other on an unused portion of the film. I n applying the finger, palm, or sole to the paper care must be taken t o avoid dragging it while in contact, for a smudged print is the inevitable result. I n general, it is preferable that all the steps in printing should be controlled by the operator alone, the subject being directed to relax the part being printed. A print of good quality shows the epidermal ridges cleanly defined, and its expanse is sufficient to include all the features of the particular area. I n making prints it is well to inspect each one and to prepare duplicates when their need is indicated. DERMATOGLYPHIC PRIWTS 37 Methods of interpreting the dermatoglyphic features are presented in the following selected references : palmar features, in Cummins et al., ’29, Am. Jour. Phys. Anthrop., vol. 12, pp. 4 1 5 4 7 3 ; finger prints, in Galton’s “Finger prints,” ’92, Macmillan ; plantar features, in Wilder and Wentworth, “Personal identification,” ’18, Badger. SPECIFIC PROCEDURES While it is obvious that the collector will record the customary d a t a regarding his subjects, providing each individual with an identifying number entered in the written record, it may not be amiss to emphasize the numbering of the prints. Every sheet of prints should carry the number of the individual. Fingers Of all the prints, those of the fingers a r e made with greatest ease. They ar e prepared i n the form technically known as ‘rolled’ prints, as distinguished from ‘plain’ or ‘dab’ impressions. A plain print represents only that p a r t of the ball of the digit which effects contact in pressing it directly against a rigid, plane surface. Rolled prints, as the name suggests, a r e made by rolling the terminal segment of the digit, both in inking a n d printing, so as to include the marginal portions which a r e lacking in plain prints. The operator grasps the digit, the subject’s hand being relaxed and passive, gently applies the margin of the terminal segment to the ink film, and then rocks the digit so that the ball and opposite margin a r e successively inked. The same rocking o r rolling motion is followed in printing, yielding a print which includes the entire apical configuration reduced to a flat surface. It should be noted that a single rolling accomplishes the purpose, and that its repetition either in inking o r printing is to be avoided. The whole terminal segment should be inked and printed on its palmar and marginal surfaces, otherwise important features of the apical configuration may be omitted. Rolled prints usually have a 38 HAROLD CUMMINS transverse dimension about double that of plain impressions of the same digit. The digits are printed in their natural order, being placed most conveniently at the bottom of the sheet bearing the print of the corresponding hand. Since the print of the whole hand includes plain impressions of all the digits except the thumb, the correctness of the sequence of the separate rolled prints may be verified, and there is no need to attach identifying marks to the separate rolled prints. Palms If the palm is simply pressed against the ink film and then transferred to paper, the resulting print is commonly so incomplete as to be almost useless. Certain important dermatoglyphic features usually escape inking in this procedure : the configuration in the central ‘hollow’ of the palm; the configurations along the distal margin, in relation to the bases of the digits; the cohfigurations on the upturned ulnar margin; the configurations in the extreme proximal territory of ridged skin, at the wrist. An adequate palm print may be compared to a rolled print of the finger tip, since special precaution is taken to insure printing of the entire palm in one continuous expanse. Strong’s method involves the use of a resilient pressure pad or cushion in inking and printing. Ink is applied to a sheet of thin waxed paper, and with this resting on the pad, the palm is pressed upon it. The cushion being yielding, the irregular reliefs .of the palm are thus brought into contact, and a repetition of the process, but substituting print paper, is followed in printing. Prints thus prepared are generally excellent in defhition, as well as complete. The results have been found hardly less satisfactory when the cushion is employed only in printing, ink being rolled directly on the hand. This substitute procedure saves considerable time, and its only drawback is that an even distribution of ink is not always attained. The Strong cushion is but one of the numerous methods which have been suggested for the same end. DERMATOGLYPHIC PRIKTS 39 Lacking the pressure pad, one may, for example, turn the subject’s inked palm upward, lay the paper upon it, and impress the operator’s own palm (with its axis oblique to that of the subject’s) against the paper in such a way as to obtain an equalized pressure throughout. Another method involves winding the paper on a cylinder, which is then grasped by the inked hand of the subject. A t least one print of each hand should be complete in all respects, and this or another print should include the fingers, naturally extended. Attention to completeness of inking and care in impressing the inked surface are essential. Soles Sole prints also may be described a s rolled and plain. A plain sole print represents the tread area alone, and certain features ordinarily escape registration in such prints. Four important configuration areas occur on the ball of the foot (hallucal and three interdigital areas), and these areas a r e usually well displayed in plain (tread-area) prints. B y a little added care in inking and printing, the impressions may be rendered much more useful. The inked roller should be passed over the region at the distal border of the sole, along the very bases of the toes, as well as along the margins of the foot in which ridged skin is extended upward from the sole. By exercising ingenuity in pressing the paper against the foot, the entire inked region may be registered in a single print. If this procedure fails to yield a satisfactory result, separate regional impressions should be made, especially of the zone bordering the bases of the toes and of the fibular margin (the latter to insure a record of the configurations in the hypothenar area). Toes Toe prints, except in the instance of the great toe, are generally unsatisfactory, owing to obvious difficulties in manipu1at.ing these digits. Apparently the only solution to this refractory problem is to apply ink by cautious swabbing (with 40 HAROLD CUMMINS the operator’s fingers), and to print by using small slips of paper which may be pressed against and around the balls of the toes, a separate slip for each print. An impression secured in this manner should be the equivalent of a rolled finger print. Only an occasional print will be completely successful; it is advisable, therefore, to make several impressions of each toe and to preserve all of them, since even the best one may prove to lack some detail that may be supplied from the duplicates. Each print requires a notation of the digit from which it comes. SUMMARY This note presents a brief technical guide for the preparation of prints of the fingers, palm, toes, and sole as records of the dermatoglyphic features. It is introduced by a plea that prints be obtained more generally in racial studies. Attention is directed to the fact that dermatoglyphic records have been commonly neglected in assembling material for racial analyses, notwithstanding the simplicity of print maki n g and the obvious utility of these records in extending the variety of somatic traits registered f o r a racial sample.